Results of Phase 3 DEFINE and CONFIRM Studies Support
Dimethyl Fumarate's Potential as a Strong Option for MS
Treatment

WESTON, Mass.--(BUSINESS WIRE)--Sep 19, 2012 - Today
Biogen Idec (NASDAQ: BIIB) announced that detailed results from
its two pivotal clinical trials evaluating oral BG-12 (dimethyl
fumarate) for the treatment of multiple sclerosis (MS) were
published in the Sept. 20, 2012 issue of The New England Journal
of Medicine (NEJM).

Data from the Phase 3 DEFINE and CONFIRM studies show that
dimethyl fumarate (240 mg), administered twice daily (BID) or three
times daily (TID), demonstrated significant and clinically
meaningful reductions in MS relapses and brain lesions in patients
with relapsing-remitting multiple sclerosis (RRMS) compared to
placebo, as well as showed benefit in slowing the progression of
the disease. Dimethyl fumarate is currently under review by
regulatory authorities in the United States, European Union,
Australia, Canada and Switzerland.

“The publication of both dimethyl fumarate pivotal studies
in NEJM is another achievement for this important investigational
therapy,” said Katherine Dawson, M.D., senior medical
director, Biogen Idec Neurology Research and Development and Biogen
Idec lead author on both dimethyl fumarate manuscripts in NEJM.
“The data from its clinical development program consistently
indicate that dimethyl fumarate may provide tangible benefits and
address existing treatment needs of people living with MS. We are
working closely with regulatory authorities across the globe with
the aim of making the review of dimethyl fumarate as quick as
possible.”

DEFINE and CONFIRM Efficacy Results

Together, the DEFINE and CONFIRM manuscripts in NEJM summarize
the positive Phase 3 clinical data set for dimethyl fumarate, which
formed the foundation for its regulatory filings around the
world.

DEFINE was a two-year global study that evaluated dimethyl
fumarate (240 mg, BID or TID) compared to placebo in people with
RRMS. Results showed that both dimethyl fumarate BID and TID met
the study's primary endpoint by significantly reducing the
proportion of patients who relapsed by 49 percent and 50 percent
(p<0.0001 for both; reported in NEJM as <0.001 due to journal
requirement that p-values smaller than 0.001 be reported as
p<0.001), respectively, at two years compared to placebo. Both
dosing regimens also met all secondary endpoints in the study.

“Because MS is a chronic disease, we look for treatment
options that not only control relapses but also slow patients'
disease progression for as long as possible,” said Ralf Gold,
Ph.D., professor/chair of the Department of Neurology at St.
Josef-Hospital/Ruhr-University in Bochum, Germany, and lead author
on the DEFINE manuscript in NEJM. “In DEFINE, dimethyl
fumarate demonstrated efficacy, as well as positive safety and
tolerability profiles, which is a very attractive combination for
an MS treatment.”

Like DEFINE, CONFIRM was a two-year global clinical trial that
investigated dimethyl fumarate (240 mg, BID or TID) versus placebo
in people with RRMS. The study also included an active reference
comparator of glatiramer acetate (GA; 20 mg subcutaneous daily
injection) versus placebo. Results showed that both dimethyl
fumarate BID and TID met the study's primary endpoint by
significantly reducing annualized relapse rate (ARR) by 44 percent
and 51 percent (p<0.0001 for both; reported in NEJM as
p<0.001 due to journal requirement that p-values smaller than
0.001 be reported as p<0.001), respectively, versus placebo at
two years. In addition, both dosing regimens of dimethyl fumarate
met all secondary relapse and magnetic resonance imaging (MRI)
endpoints in the study. While not statistically significant,
dimethyl fumarate showed a clinically meaningful reduction in
12-week confirmed disability progression as measured by the
Expanded Disability Status Scale (EDSS).

The GA data versus placebo in CONFIRM were generally consistent
with its product labeling.

“Results of the CONFIRM study were consistent with those
of DEFINE, demonstrating that oral dimethyl fumarate significantly
reduced MS disease activity compared to placebo and has a strong
safety profile,” said Robert J. Fox, M.D., medical director
of the Mellen Center for Multiple Sclerosis at Cleveland Clinic and
lead author on the CONFIRM manuscript in NEJM.* “I believe
that these findings support the potential of oral dimethyl fumarate
in RRMS for both treatment-naïve patients and those not
tolerating or sub-optimally responding to currently available
therapies.”

* Dr. Robert Fox is a paid advisor for Biogen Idec for
projects not related to dimethyl fumarate clinical
development.

The CONFIRM manuscript in NEJM also includes data from a
post-hoc efficacy analysis that directly compared dimethyl fumarate
to GA treatment. While CONFIRM was not designed for a formal
statistical comparison of GA versus dimethyl fumarate treatment,
this post-hoc analysis was included because it may provide helpful
information regarding dimethyl fumarate's efficacy compared to an
approved therapy for MS.

DEFINE and CONFIRM Safety Results

In DEFINE and CONFIRM, the safety profile for the dimethyl
fumarate BID and TID treatment groups was similar. The overall
incidence of adverse events (AEs), serious adverse events (SAEs)
and AEs leading to study discontinuation was similar among the
dimethyl fumarate and placebo groups in both studies.

In both studies, AEs that occurred more commonly with dimethyl
fumarate treatment were flushing and gastrointestinal (GI) events.
Flushing and GI events had the highest incidence in the first month
of the study and decreased thereafter. The most frequently reported
SAE across all treatment groups in both studies was MS relapse.

There was no increase in serious infections or malignancies in
the dimethyl fumarate groups compared to placebo in either study.
There were no opportunistic infections in the dimethyl fumarate
groups. Laboratory analysis in both studies found mean white blood
cell counts (WBC) and lymphocyte counts decreased during the first
year in dimethyl fumarate-treated patients and then plateaued,
remaining within the normal range throughout.

The full manuscripts, called “Placebo-Controlled Phase 3
Study of Oral BG-12 for Relapsing Multiple Sclerosis”
(DEFINE) and “Placebo-Controlled Phase 3 Study of Oral BG-12
or Glatiramer in Multiple Sclerosis” (CONFIRM), can be found
on the NEJM website at
http://www.nejm.org.

About DEFINE

DEFINE (Determination of the Efficacy and
safety of
oral Fumarate IN rElapsing-remitting
MS) was a global, randomized, double-blind, placebo-controlled,
dose-comparison study to determine the efficacy and safety of
dimethyl fumarate (240 mg, BID or TID) and enrolled 1,237 people
with RRMS. The primary objective was to determine if dimethyl
fumarate was effective in reducing the proportion of relapsing
patients at two years. Secondary endpoints included reduction in
the number of new or newly enlarging T2-hyperintense lesions and
new gadolinium-enhancing (Gd+) lesions as measured by MRI,
reduction in ARR, and reduction of disability progression as
measured by EDSS. Additional endpoints included the safety and
tolerability of dimethyl fumarate. Detailed results from DEFINE
were presented at the 5th Joint Triennial Congress
of the European and Americas Committees on Treatment and Research
in Multiple Sclerosis (ECTRIMS and ACTRIMS) in October 2011.

About CONFIRM

CONFIRM (COmparator and aN oral Fumarate
In Relapsing-remitting MS) was a global,
randomized, double-blind, placebo-controlled, dose-comparison study
to determine the efficacy and safety of dimethyl fumarate and
enrolled 1,430 people with RRMS. The study evaluated two dose
regimens of dimethyl fumarate, 240 mg BID and 240 mg TID, as well
as a reference comparator of GA (20 mg subcutaneous daily
injection). Both dimethyl fumarate and GA groups were evaluated
versus placebo. The primary objective was to determine whether
BG-12 was effective in reducing the rate of clinical relapses at
two years. Secondary endpoints at two years included reduction in:
the number of new or newly enlarging T2-hyperintense lesions and
the number of non-enhancing T1-hypointense lesions (MRI scans were
obtained at a cohort of sites); the proportion of patients who
relapsed; and in progression of disability as measured by EDSS.
Safety and tolerability of BG-12 were also assessed. Detailed
results from CONFIRM were presented at the
64th Annual Meeting of the American Academy of
Neurology (AAN) in April 2012.

About Dimethyl Fumarate

Dimethyl fumarate, also known as BG-12, is an investigational
oral therapy in late-stage clinical development for the treatment
of relapsing-remitting multiple sclerosis (RRMS), the most common
form of MS. Dimethyl fumarate is the only currently known
investigational compound for the treatment of RRMS that has
experimentally demonstrated activation of the Nrf-2 pathway.

In 2011 and 2012, Biogen Idec announced positive data from
DEFINE and CONFIRM, two global, placebo-controlled Phase 3 clinical
trials that evaluated 240 mg of dimethyl fumarate, administered
either twice a day or three times a day, for two
years. Dimethyl fumarate is currently under review by
regulatory authorities in the United States, European Union,
Australia, Canada and Switzerland.

About Biogen Idec

Through cutting-edge science and medicine, Biogen
Idec discovers, develops and delivers to patients worldwide
innovative therapies for the treatment of neurodegenerative
diseases, hemophilia and autoimmune disorders. Founded in
1978, Biogen Idec is the world's oldest independent
biotechnology company. Patients worldwide benefit from its leading
multiple sclerosis therapies, and the company generates more
than $5 billion in annual revenues. For product labeling,
press releases and additional information about the company, please
visit
www.biogenidec.com.

Safe Harbor

This press release includes forward-looking statements,
including statements about the commercialization of BG-12 (dimethyl
fumarate) in MS. These forward-looking statements may be
accompanied by such words as "anticipate," "believe," "estimate,"
"expect," "forecast," "intend," "may," "plan,"
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